Title: Fiber-Based Miniature Strain Sensor with Fast Response and Low Hysteresis

Ruixuan Wang, Tong Qiu, Yujing Zhang, Michael Rein, Alexander Stolyarov, Junru Zhang, Gary D. Seidel, Blake N. Johnson, Anbo Wang, Xiaoting Jia
Department of Aerospace and Ocean Engineering
Virginia Tech
Blacksburg, VA 24060

Advanced Functional Materials Volume 43, Issue 40, 2024 pp. 2403918

Abstract
Flexible and stretchable strain sensors are in high demand in sports performance monitoring, structural health monitoring, and biomedical applications. However, existing stretchable soft sensors, primarily based on soft polymer materials, often suffer from drawbacks, including high hysteresis, low durability, and delayed response. To overcome these limitations, a stretchable miniature fiber sensor comprised of a stretchable core tightly coiled with parallel conductive wires is introduced. This fiber sensor is flexible and stretchable while exhibiting low hysteresis, a remarkable theoretical resolution of 0.015%, a response time of <30 milliseconds, and excellent stability after extensive cycling tests of over 16 000 cycles. To understand and predict the capacitive sensor response of the proposed sensor, an analytical expression is derived and proved to have good agreements with both experimental results and numerical simulation. The potential of the strain sensor as a wearable device is demonstrated by embedding it into belts, gloves, and knee protectors. Additionally, the sensor can extend its applications beyond wearable devices, as demonstrated by its integration into bladder and life safety rope monitoring systems. The sensor is envisioned to have applications in the field of sports performance evaluations, health care monitoring, and structural safety assessments.

Key words: Flexible Strain Sensors Low Hysteresis